The Evolution
22
neither "hospital" nor "blade," "breadknife" has a .00005 to .000004
edge over "scalpel," which is 12.5:1.
Now if "hospital" occurs the probability of "scalpel" increases
from .000004 to .01, as is indicated by the "hospital" profile, leading
to the new ratio of .00005 to .01, which is a 1:200 edge in favor of
"scalpel." This means that if "blade" were ambiguously perceived,
"scalpel" would be more likely than "breadknife" by this 200-fold
factor. Actually the edge would be even greater since the zero proba-
bility that "hospital" ascribes to "breadknife" indicates that its
probability is probably below .00005. In other words the addition of
"hospital" would dramatically alter the probabilities so as to make
the intersected concept, "scalpel," the preferred disambiguation of
memory.
Now note that this is in sharp contrast to what happened earlier
when these same values were plugged into the equivalent Type III inter-
section. The most striking fact to emerge from that analysis was that
the presence or absence of "Florida" as a concept preceding "eggs" had
only the slightest effect on the probability of the intersected concept
"orange juice"; the probability of "orange juice" rose relative to the
other concepts, but only by the slightest amount.
From all of this a key principle emerges: A memory optimized for
prediction should find Type III intersection tasks (e.g. name something
associated with both "Florida" and "eggs") more difficult to carry out